Detection of location and size of water tree in XLPE cables by frequency response analysis: A simulation study

Water tree is a type of degradation in power cable resulting in the breakdown of insulation. This paper attempts to develop a method for water tree diagnosis of cable insulation by analysis of cable impedance in frequency domain. A distributed model of 66 kV XLPE power cable is modelled and impedance characteristics is obtained for various degradations by sweep frequency response analysis using Multisim software. The water tree parameters are obtained by FEM modelling of cable in COMSOL software and impedance of the cable is analyzed for water trees of different amounts at various locations in cable insulation. The analysis yields a generalized method for detection and determination of extent and location of water tree in cable insulation.